<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Vue_Counter</title>
    <link rel="stylesheet" href="index.css"/>
</head>
<body>
    <div id="app" >
        <div class="input-num">
            <button @click="sub">
                -
            </button>
            <span>{{ num }}</span>
            <button @click="add">
                +
            </button>
        </div>
    </div>
    <!-- 开发环境版本，包含了有帮助的命令行警告 -->
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script>
    <script>
        var app = new Vue({
            el:"#app", 
            data:{
                num:1
            },
            methods:{
                add:function(){
                   // console.log('add')
                   if(this.num < 10){
                       this.num++;
                   } else {
                       alert('别点了xd！没了！');
                   }
                },
                sub:function(){
                    //  console.log('sub')
                    if(this.num > 0){
                        this.num--;
                    } else {
                        alert('别点了xd！没了！');
                    }
            
                }
            }
        })
    </script>
</body>
</html>